Nine mountain climbers died on Mt. Everest this year. Those that made it back to their Himalayan base camp and lifted out of danger (by helicopter) lost toes, fingers, nose and body tissue damaged by frontbite. The foot of the climbers were well protected. Each climber had don on at least two pairs of socks, a boot liner, an inner boot and an outer boot for insulation against the elements. Even with such protection, frostbite can occur. Skin protection against the cold is a concern not only of mountain climbers to the highest peak of the world, but also of great concern to military strategist planing training maneuvers in the Arctic and Antarctic environments, to scientist working in cold regions of the world, to radar workers manning equipment in Siberia and North Dakota, to sports enthusiast (skiers, hunters, sled dog racers, etc.) and to people living everyday lives in the Arctic and Antarctic regions. NASA is concern with protecting man in the cold environments of deep space. The Navy is concern with ways to protect man in the cold water environments below the ice surface. The Army has its Cold Region Research Environment Laboratory and one of its mission is to evaluated materials and fabric for protecting the human body against cold.
One of the most advanced cold weather boots available is fitted with a shell, a layer of thermal insole, a moisture trap layer with a top layer of foam insulation surrounding the feet. Body heat is trapped in (a) a warm air insulation matrix surrounding the foot surface, followed by (b) a high moisture vapor transfer (high air permeability lining fabric, over a (c) high efficiency foam insulation, (d) a high moisture vapor transfer and low air permeability outer fabric, and (e) a shell fabric which deflects the wind and stabilizes the insulating air. Another equally advanced cold weather boot is described in U.S. Pat. No.: 4,845,862.
Up to the present time, cold weather boots are not capable of preventing frostbite of the foot. The causes of frostbite are poor blood circulation cause by the compaction of foot and compacted foot moisture latent insulating materials. The compacted insulating material also allows for rapid conduction of heat away from the foot by the presence of excessive moisture. In some cold weather boots, foot moisture is allowed to collect and freeze directly below the foot insulating layer. Once foot moisture the collects and freezes, it can form a conducting path for heat to leave the boot. Frostbite results when the foot is allowed to remain in prolong extreme cold conditions. Unless the moisture latent socks and any frozen moisture inside the boot and below the insulating layer are removed and the foot is kept warmed and dried, the water in the foot is in danger of freezing into crystals of ice. The need to protect the foot also applies to the other parts of the human skin that may be exposed to the cold, such as the face, the neck, the fingers, the nose, the ears, and other parts of the body.
U.S. Pat. No. 3,660,849 discloses a insulative deep submergence diving suit based on a flexible supporting surface layer substantially fully covering a very low modulus gel of SIS and SBS block copolymer-mineral oil and glass microbubble filler. The problem with such a gel suit made from a SIS and SBS is that the suit can easy break apart, rip, or tear under its own weight without the flexible support. The flexible support covering the inside surface of the suitable also isolates the gel.